FOOD FOR THOUGHT How big can one PiaF server scale up to?

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The company I work for is splitting into two different companies. The parent company will retain the existing behemoth Avaya phone system, and the new company will be going with something new. At some point, I'm sure I'll be asked for input. I'd like to recommend PiaF but that got me to thinking - how big can one Asterisk/FreePBX scale up to?

I know that's a pretty open-ended question as different applications could have wildly varying requirements. However, are there any rules of thumb for "general" scenarios? Could one server handle, say 400 SIP phones?
 

kenn10

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I don't think there is any direct answer to your question. Going from Avaya Definity to Asterisk will be daunting -- both to administrators and users. If your users are used to shared call appearances, get ready for the axes and pitchforks coming at you. Most large corporate environments have many boss/secretary scenarios using shared appearances on their phones. Asterisk does not yet support this.

I think that 400 users on one server, even a Xeon quad-core server might be a little risky. Of course that depends on the number of simultaneous calls, call centers, trunk arrangements, etc. I personally feel that with over 200 subscribers, you should look at a cluster environment which can scale as you grow. A cluster cannot currently be directly addressed by PIAF but there are quite a few large campus environments that use Asterisk clusters.

When you start reading the white papers on clustering, it gets quite interesting.

Here are some interesting links: http://opensips-open-sip-server.1449251.n2.nabble.com/Asterisk-Cluster-Scenario-td5569616.html

and http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDgQFjAA&url=http://www.ntegratedsolutions.com/wp-content/uploads/2012/07/Using_DUNDi_with_a_Cluster_of_Asterisk_Servers.pdf&ei=Wj8fU8eVMtCfkAewxICYAg&usg=AFQjCNFSHsPiRJL5G0nBGF2ZDolN97bYHg&sig2=41fjHZ_V-ML-MFZ_9Cs8jA

and http://myhandbook-technical.blogspot.com/2011/12/how-to-build-asterisk-cluster.html

Going the Asterisk route will be much less expensive than staying with a proprietary system but you also need to consider repair, maintenance, and remote support in the equation. If the split corporation is in one facility, self maintenance might be OK but you need someone dedicated to handling maintenance and support. So you have lots to think about.

Good luck!
 

jroper

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Hi

We have built a system for a WISP, and they are running 1500 customers on FreePBX routing via A2Billing. Surprisingly the issue is not so much the load with calls in progress, this is quite low as long as ring groups and queues are not being used, but the act of generating all the text files (clicking reload) for a system with more than a 1000 extensions on it can take a while depending on the hardware, and in one system, some years ago, we have to extend php timeouts as it was taking so long.

One single Asterisk system on server class hardware will have no issues with 400 SIP phones, we run much more than this on A2Billing all the time on not particularly powerful hardware. If you want 4000, then it might get a bit tricky for the reasons mentioned above.

Joe
 
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I think your issue is more of a political one than a technical choice. I'm sure there are a few exceptions but you and your colleagues who have responsibility for this new platform recommendation or implementation are unlikely to be fired if you choose a new Avaya or Cisco system. I know how that sounds especially on this forum but the employee's are use to the phones working a certain way. A company split like this has lots of issues and one of them should not be the phone system. You don't want the hindsight spotlight to be on you! I just don't like the fundamental Asterisk architecture when it comes to scaling and mission critical situations. You want a large firm that has a professional project management organization. Others may feel differently but I'm telling you what I would do.
Splits usually involve management changes and efforts to "streamline" the organization. You don't want to be part of the streamlining if things go bad. Bring in some major players, see what they offer and let someone else make the decision....
 

wardmundy

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:iagree: A better approach might be to start peeling off pieces of the phone system to handle with PBX in a Flash. Choose components that don't fundamentally change the way your employees currently do business. Then add value with functions like text-to-speech and speech-to-text to get everyone excited about the platform. Then you can gradually add more pieces down the road. As Brian said, you don't want to be the one that catches the arrows in your back for all the inherent problems of a major reorganization.
 

atsak

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I think another key issue is to say - OK - everyone - Cisco/Avaya will be, oh let's say $100,000 for this install. Asterisk/PIAF will be half that. Cisco Avaya will just work. Asterisk/PIAF will work as well, but have a couple weeks of initial headaches then a minor issue every 6 months or so. That's fairly consistent with my experience with installs. The issues are usually things like a failed trunk or a failed phone. A couple of times I've seen asterisk just die but the outage was only 5 minutes long or so. Therefore, the question that gets answered above my pay grade, as they say in the military, is what is that worth? Every time but once it's been we'll go with Asterisk, because it does not cost $50,000 to be out for 5 or 10 minutes a year and a couple weeks of adjustment pain for staff to have every imaginable feature.
 
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Oh, I understand all of the political issue involved.

I'm just asking because I know as the resident open-source expert (I know how to spell it) that I'll be asked if an open-source solution would work. I doubt I'll have any part in the ownership of the phone system whichever way it goes.

And bryankelly, yes there will be great weeping and gnashing of teeth amongst the users if the phones operate the teeniest bit differently than what they expect. However, part of the reason for the split is that the half that is splitting off thinks they are being saddled with the costs of "gold plated" solutions from corporate. They like free - a lot (trying to explain total cost of ownership to them is wasting breath - I've been trying for 20 years). The users have been told that they need to "embrace change" (translation - whining about changes due to the split will be frowned upon).

The user's phones needs will be very simple. Other than a couple of sales and customer service type folks, I expect phone usage to be pretty light. I don't think anyone on that side of the business uses any of the fancy features of the Avaya today.
 
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Oh, I understand all of the political issue involved.

I'm just asking because I know as the resident open-source expert (I know how to spell it) that I'll be asked if an open-source solution would work. I doubt I'll have any part in the ownership of the phone system whichever way it goes.

And bryankelly, yes there will be great weeping and gnashing of teeth amongst the users if the phones operate the teeniest bit differently than what they expect. However, part of the reason for the split is that the half that is splitting off thinks they are being saddled with the costs of "gold plated" solutions from corporate. They like free - a lot (trying to explain total cost of ownership to them is wasting breath - I've been trying for 20 years). The users have been told that they need to "embrace change" (translation - whining about changes due to the split will be frowned upon).

The user's phones needs will be very simple. Other than a couple of sales and customer service type folks, I expect phone usage to be pretty light. I don't think anyone on that side of the business uses any of the fancy features of the Avaya today.

Sounds like you've got the picture..... just keep a safe distance! Good Luck!
 

DarkQuark

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Here is my 2 cents having worked with FPBX/PIAF and large VOIP systems ( talking upwards of 10k phones). For that many phones I would stick with something like CallManager. Yes it can be expensive but it works more like your Avaya PBX (shared line appearances) and the support as well as the system itself is rock solid. As an IT guy you have to think of worse case scenario and what the business impact would be. I think PIAF/FPBX is equally as good but it really shines with smaller systems where something like CallManager shines with larger systems.
 

hbonath

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Another comment to throw in would be to carve up multiple boxes into departments behind a frontend. jroper helped us get our a2billing going for our hosted PBX platform and we have close to 1000 handsets distributed among company specific PBX VMs. This can be adapted for a single business use. Asterisk can also trunk between boxes so say the 100-199 range is on PBX A, the 200-299 range on PBX B and so on. That way you can have full routing and things like a parking lot for each department etc. and then scaling is easy - even easier if using a clustered VM approach.
I'm not saying you would even need to use a2billing - but since it runs on asterisk it's relevant.
 

drdrew

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Our biggest instance is a 180 seater debt collection call centre averaging about 60 - 100 concurrent calls (all of them recorded) from 7am to 6pm. We use g729 for everything except recordings which are saved in wav49 (wav-encapsulated GSM). This means all our sounds, MOH and so forth are in g729 which reduces transcoding overhead quite significantly with these amounts of users. We have also recompiled Asterisk with a lot of apps excluded. The most important one to exclude is SQLLite (but keep SQLlite3) as this caused channel hangups when going past 50 concurrent calls.

The server running this is a HP DL380 G6 with 2 x Xeon 2.4Ghz Quad Core and 12GB of RAM. Then we have four 146Gb SAS drives split into 2 x RAID 1 arrays - one for the PBX software and OS and the other for the recordings. We are running PAIF 2.0.6.4 64 bit with Asterisk 11.6 and we have zero issues. Call quality is great, no call cuts and recordings sound great.

My performance enhancing tips:
1) remove SQLlite completely. You can do this by adding the no_load part in modules.conf or by recompiling Asterisk (not recommended unless you know what you are doing)
2) have the same codec and sound format all the way through e.g. ulaw or g729 or whatever. If they differ that means transcoding
3) Disable the full log completely unless you really need it. Leave messages for security on otherwise Fail2ban doesn't work.
4) Don't load any resource heavy apps on the server like CDR-Stats (the one that uses Mongo). You will regret it!
5) Don't let the server do anything it shouldn't - no DNS, no NOTHING.
6) Explicitly allow only local IP's, your provider IP's (SIP and DNS) and your own remote static IP. That's it - drop all other input. Then you can open all the relevant ports just to those IP's. This lets your firewall work much less than when you have all sorts of complex rules and chains and also prevents strange issues down the road. This also helps prevents things like DNS attacks and hacking in general.
7) If anything add as much RAM as possible. It is by far the most significant contributor to bottlenecks. We have had asterisk die on us with 10% CPU usage because of too little RAM.
8) Allow reinvites from your phones if you aren't recording everything. That lets Asterisk drop out of the media path and allows much, much higher concurrencies.
9) If you are using G729 make sure your codec payload matches your provider's. The default on Asterisk is 20ms. This is defined by using the allow=g729:20 field in your trunk settings. If they don't match - that also means transcoding and bad call quality.

If I think of anything else I will add it later. Hope this helps!
 

phoneguy

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We run stock FreePBX systems with 5000 users and 500 plus concurrent calls with no modifications or anything special. Its not difficult. I have personally watched Asterisk boxes send out over 6000 concurrent calls for 10 hours a day before.
 

nightstryke

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We run stock FreePBX systems with 5000 users and 500 plus concurrent calls with no modifications or anything special. Its not difficult. I have personally watched Asterisk boxes send out over 6000 concurrent calls for 10 hours a day before.

Really? What's your setup as far as System Specs?
 

Asher

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You know it's coming, configure one with a couple extensions to be ready to demo not so much how it works, but what the differences are. Document them, let management know about them.

As far as shared appearance, we may be using different terminology, because, I can add BLF showing status of another extension on my Cisco 508g phones.
 

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